Method of freezing salted meat products

ABSTRACT

A method of freezing a cured protein product to preventing or reducing purge produced from such frozen cured protein products is provided. The method includes the steps of preparing a brine including a cruciferous oil and a glycol, cooling the brine, and subjecting the cured protein product to the cooled brine.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method of freezing cured protein products, such as salted or smoked meat products by exposing them to a brine, more particularly, to a freezing method that prevents or reduces purge produced from the frozen salted meat products and weight loss of such products.

[0003] 2. Description of the Related Art

[0004] Conventional methods of freezing cured protein products such as cured meat involve using air, blast freezing, tunnel freezing, or brine (antifreeze solution) which is cooled by a cooling medium, or immersing the cured meat products in liquid nitrogen or liquid carbon dioxide. These freezing methods result in a great amount of purge or drip from the salted or cured meat products after thawing as the consequence of destruction of the tissues and cells. The destruction of tissues and cells causes loss of the meat weights and deterioration in taste and texture. This consequence becomes worse when the de-frozen salted and smoked meat products have to be frozen again from time to time.

[0005] U.S. Pat. No. 4,601,909 to Nagoshi discloses a Methods of Freezing Fishery Products. The method includes the steps of preparing a brine containing rapeseed oil, propylene glycol, calcium chloride and water, cooling the brine and immersing the seafood in the cooled brine until it is frozen. Such a brine prevents or reduces the breakdown of muscle tissue in the seafood due to ice crystal formation. The resultant deterioration in quality from freezing is thus prevented.

[0006] A similar process for Quick Freezing of meat is disclosed and claimed in U.S. Pat. No. 4,654,217 issued to the same inventor. The process disclosed in this later patent similar to that disclosed in the earlier patent except that it is applicable to beef, poultry, pork and the like.

[0007] U.S. Pat. No. 4,657,768 to Nagoshi discloses a Freezing Method for Perishable Foods which includes placing a perishable food in a heat conducting container and causing the other surface of the heat conducting container to contact the cooled brine or a liquified gas. Accordingly, the perishable food is frozen quickly without immersion.

[0008] U.S. Pat. No. 4,689,963 to Sakai relates to a Method of Freezing Foods. The Sakai method is similar to the method of the Nagoshi method except that a layer of brine is placed in the heat conducting container along with the perishable food.

[0009] U.S. Pat. Nos. 4,840,035, 4,840,034 and 5,001,047 to Liberman relate to methods of freezing sensitive body fluids, tissue samples and organs, respectively. The freezing methods described in these patents are similar to the Nagoshi method except that the freezing objects in Liberman patents are sensitive body parts for the clinical use.

[0010] There is no teaching or suggestion in any of these patents that the processes disclosed can prevent or reduce the amount of purge or drip produced by salted and smoked frozen meat products after thawing thereby maintaining the flavor and texture of such salted meat products.

[0011] Accordingly, it is desirable to provide a process for preventing or reducing purge produced from frozen salted and smoked meat products after thawing.

SUMMARY OF THE INVENTION

[0012] An object of the present invention is to provide a method of preventing or reducing purge produced during the course of freezing cured protein products. The method comprises the steps of preparing a brine including a cruciferous oil; cooling the brine to a temperature between about −22° F. and −43.6° F.; exposing the surface of a cured protein product, such as salted or smoked meat, to the brine by placing the meat product in a perforated container for a period that such protein product is completely frozen.

[0013] Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0014] As used herein, the term “cured protein product” means a product containing a substantial amount of protein and is processed by way of, for example, salting or smoking or both, such as a salted or smoked fish.

[0015] According to the present invention, the brine solution used for freezing the salted and cured meat products includes a cruciferous oil. In a preferred embodiment, oil from a plant of the genus Brassica is used. These oils include, but are not limited to, oil of Brassica campestris, otherwise known as rapeseed oil, and oil of Brassica hirta, also known as mustard oil.

[0016] Repessed oil has a solidification point of 14° F. (−10° C.), a specific gravity at 59° F. (15° C.) of 0.915, a refractive index at 122° F. (50° C.) of 1.4706, an iodine value of 98.6 and a saponification value of 174.7. The oil includes about 1% palmitic acid, the only saturated component of the oil, about 32% oleic acid, about 15 % linoleic acid, about 1 % linolenic acid and about 50% erucic acid. Palmitic acid, otherwise known as hexadecanoic acid is a saturated fatty acid having 16 carbon atoms and a molecular weight of 256.4.

[0017] Oleic acid, also known as (Z)-9-octadecenoic acid, has 18 carbon atoms and a molecular weight of 282.5. The position of unsaturation is between the ninth and tenth carbon atoms in the chain. The molecule has a cis configuration.

[0018] Linoleic acid has two positions of unsaturation and is also known as cis.cis-9,12-octadecadienoic acid. The acid has 18 carbon atoms and a molecular weight of 280.5.

[0019] Linolenic acid has three positions of unsaturation and is also known as (Z.Z.Z)-9.12.1 5-octadecatrienoic acid. Linolenic acid has 18 carbon atoms and a molecular weight of 278.4.

[0020] Erucic acid, a major component of the oils of the genus Brassica, is also known as (Z)-13-docosenoic acid. Erucic acid has 22 carbon atoms with one position of unsaturation and a molecular weight of 338.6.

[0021] Mustard oil is similar. Mustard oil has a specific gravity at 59° F. of 0.9145. a refractive index at 122° F. of 1.475, an iodine value of 102 and a saponification value of 174. Mustard oil includes 1.3% by weight myristic acid, the only saturated acid, 27.2% by weight oleic acid, 16.6% by weight linoleic acid, 1.8% by weight linolenic acid, 1.1 % by weight behenic acid, 1.0% by weight lignoceric acid and 51.0% by weight erucic acid. Myristic acid, also known as tetradecanoic acid. has 14 carbon atoms and a molecular weight of 228.4.

[0022] Behenic acid is also known as docosanoic acid. It has 22 carbon atoms and a molecular weight of 340.6. Lignoceric acid, also known as tetracosanoic acid, has 24 carbon atoms and a molecular weight of 368.6. The other components of mustard oil are described above.

[0023] The oil is used in an amount less than about 1% by weight, more preferably less than about 0.8% by weight and most preferably between about 0.1 and 0.5% by weight of the brine.

[0024] It is to be understood that oils other than rapeseed oil and mustard oil can be used in accordance with the invention. For example, synthetic oils having the characteristics described would be useful. In addition, the manner in which the oils function is described in detail below and it will be readily apparent that other oils will function acceptably in accordance with the invention and can be readily determined.

[0025] In addition to the cruciferous oil, the brine also generally includes a glycol, an inorganic salt and water. Suitable glycols include, but are not limited to, ethylene glycol, propylene glycol. benzylene glycol, butylene glycol. diethylene glycol, diphenyl glycol. ethylidene glycol, and the like. Any glycol can be used alone or in combination with other glycols. Propylene glycol is used in a preferred embodiment. The glycol component is present in an amount between about 30 and 50% by weight of the brine, more preferably between about 35 and 45% by weight and most preferably in an amount of about 40% by weight.

[0026] Salts which are useful in accordance with the invention include, but are not limited to, calcium chloride, calcium bromide, calcium iodide, potassium chloride, potassium bromide, potassium iodide and the like. In a preferred embodiment. calcium chloride is used. The salt is present in an amount between about 5 and 15% by weight of the brine, more preferably in an amount between about 7 and 13% by weight and most preferably in an amount of about 10% by weight.

[0027] Water is present in an amount between about 40 and 60% by weight, more preferably in an amount between about 45 and 55% by weight and most preferably in an amount of about 50% by weight.

[0028] In an especially preferred embodiment, the brine includes between about 0.1 and 0.5% by weight cruciferous oil, about 40% by weight propylene glycol. about 10% by weight calcium chloride and a balance of water. The cruciferous oil is preferably rapeseed oil.

[0029] It is presently believed that when the brine including the oil is cooled to a temperature between about −22 and −43.6° F., fine ice crystals form in the brine and are uniformly distributed. These crystals permit efficient cold transfer and an increase in the expected chilling rate of a salted meat product immersed in the brine. Consequently, the time required to chill a meat product is reduced. In a preferred embodiment, means are provided for withdrawing heat from the brine as a meat product is brought into a heat transfer relationship therewith. This permits the temperature of the brine to be maintained substantially constant when a meat product is introduced. Accordingly, the meat product can be chilled rapidly with minimum formation of ice crystals, breakdown of cellular tissue and deterioration of the protein or meat product.

[0030] In practice, protein products such as fish, pork and beef may be cured by dry salting or being soaked in a salted solution so that the salt content of each such product is increased. This serves to preserve the meat and enhance the flavor and texture of the meat. Subsequent this salting step, the salted meat product may be further cured by way of, for example, smoking, so that the flavor and texture of the salted meat products can be further enhanced.

[0031] As a result of the above described salting, the cells of the salted meat products contain a high concentration of salt. Under a slow freezing process, the cell plasma of the salted meat product tends to freeze out fresh water first leaving the salt within the unfrozen cell plasma. The salt concentration in the unfrozen cell plasma of the slated meat products thus becomes even higher resulting in more water entering into the cells through osmosis, which eventually causes an expansion of the cell plasma volume. When the slow freezing process is completed, a large amount of ice crystals are formed, which break the cell membrane causing purge and consequential weight loss and faccidity.

[0032] To avoid or reduce purge produced in a slow freezing process thereby preserving the flavor and texture of salted or salted and smoked meat products after such products are frozen, it is crucial to employ a freezing method that rapidly and uniformly freezes the salted and cured meat products such that the volume of the cell plasma is not increased during the freezing process. The present invention achieves this object by rapidly freezing the salted or salted and smoked meat products using the above described brine.

[0033] A salted or salted and smoked meat product may be frozen by being placed in a suitable container, such as a plastic bag, which is immersed in the brine until the meat is completely frozen. Preferably, the product is vacuum packed in the container then immersed in the brine because vacuum packaged products require less time to be completely frozen. A perforated board such as a plastic mesh is preferred to carry such meat product because the entire surface of the product can be exposed to the brine in this manner. The amount of time required for freezing such meat products various depending on the type, size and the surface/weight ratio of the product, but can be readily determined by a person of ordinary skill in the art.

[0034] The salted or salted and smoked frozen meat product so produced causes much less purge and much less weight loss after thawing. In one example, the conventional freezing method results in the amount of purge about 2-3 times as much as the freezing method employed in the present invention, in other words, the present invention reduces the amount of purge produced from frozen salted or salted and smoked meat product by 2-3 folds. The advantage of the present invention in reducing purge or preventing weight loss of the salted or salted and smoked frozen meat products becomes more evident when such products are refrozen after being thawed.

[0035] The following example represents a particular embodiment of the present invention, which serves to further illustrate the present invention. It shall not be construed as limitations of various aspects of the present invention.

EXAMPLE

[0036] Fish filets were divided into three groups, Group I, Group II and Group III, each group consisting of six pieces of filets with predetermined weights. Group I was treated with conventional freezing process, Group II was treated with TRUFRESH freezing process, and Group III was kept unfrozen (fresh). Then the fish filets in Groups I and II were thawed. After thawing, all of these filets were salted and smoked by a known process. The weight losses of each piece of filets in the three groups was measured as shown in TABLE I. An average percentage of the weight loss in each group after thawing and smoking was shown in TABLE TABLE I Filet No. Weight. (Kg) Weight. (Kg) (Smoked) Weight Loss (%) Group I (frozen by conventional freezing process) 1 1.10 1.00 9.1 2 1.35 1.22 9.6 3 1.45 1.30 10.3 4 1.25 1.10 12.0 5 1.25 1.13 9.6 6 1.15 1.05 8.7 Average 1.26 1.13 9.9 Group II (frozen by TRUFRESH freezing process) 1 1.30 1.20 7.7 2 1.15 1.10 4.3 3 1.25 1.16 7.2 4 1.45 1.36 6.2 5 1.40 1.35 3.6 6 1.45 1.40 3.4 Average 1.33 1.26 5.4 Group III (unfrozen) 1 1.45 1.35 6.9 2 1.40 1.27 9.3 3 1.35 1.24 8.1 4 1.40 1.28 8.6 5 1.25 1.15 8.0 6 1.25 1.15 8.0 Average 1.35 1.24 8.1

[0037] TABLE II Group No. Weight Loss (%) Group I 9.9 Group II 5.4 Group III 8.1

[0038] The above result shows that the fish filets subject to the TRUFRESH frozen process lost weight about half as much as those subject to the conventional frozen process.

[0039] After the above described procedure, each group was again divided into three sub-groups and each sub-group was again subject to the above described three types of treatments, i.e. conventional frozen, TRUFRESH frozen and unfrozen. Loss of purge was measured in each sub-group, the results of which are shown in TABLE III. TABLE III Treatment Purge Loss (%) Group I Unfrozen 0.800 Unfrozen 0.574 TRUFRESH 0.308 TRUFRESH 0.455 Conventional 0.708 Conventional 0.667 Group II Unfrozen 0.500 Unfrozen 0.545 TRUFRESH 0.259 TRUFRESH 0.147 Conventional 0.444 Conventional 0.429 Group III Unfrozen 0.444 Unfrozen 0.394 TRUFRESH 0.242 TRUFRESH 0.313 Conventional 0.696 Conventional 0.783

[0040] In each of the above group, purge loss is significantly reduced in the sub-groups treated with TRUFRESH freezing process, whether they were previously treated with conventional or TRUFRESH freezing process, or unfrozen.

[0041] Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto. 

1. A method of freezing a cured protein product to reduce purge produced from said cured protein product comprising the steps of: preparing a brine comprising at least 0.1% by weight of cruciferous oil, between about 30 and 50% by weight of glycol. and between about 5 and 15% by weight of an inorganic salt, the balance being water; cooling the brine to a temperature between about −22 and −43.6° F.; and subjecting said cured protein product to said cooled brine.
 2. The method of claim 1, wherein the oil is extracted from a plant of the genus Brassica.
 3. The method of claim 1, wherein the oil is selected from the group consisting of rapeseed oil, mustard oil, and mixtures thereof.
 4. The method of claim 1, wherein the oil contains erucic acid as the single largest component.
 5. The method of claim 1, wherein the oil contains less than about 2% saturated components.
 6. The method of claim 1, wherein the oil is used in an amount between about 0.1 and 0.5% by weight of the brine.
 7. The method of claim 1, wherein the glycol is propylene glycol.
 8. The method of claim 1, wherein the glycol is present in an amount between about 35 and 40% by weight of the brine.
 9. The method of claim 1, wherein the salt is calcium chloride.
 10. The method of claim 1, wherein the salt is present in an amount between about 7 and 13% by weight of the brine.
 11. The method of claim 1, wherein the water is present in an amount between about 4 and 55% by weight of the brine.
 12. The method of claim 1, further comprising the steps of vacuum packaging said cured protein product.
 13. The method of claim 12, wherein said cured protein product is vacuum packaged in a plastic bag.
 14. The method of claim 1, further comprising placing said cured protein product on a perforated board such that the entire surface of said cured protein product is exposed to the brine.
 15. The method of claim 14, wherein said perforated board is a plastic mesh.
 16. The method of claim 1, wherein said cured protein product is a salted meat product.
 17. The method of claim 16, wherein said cured protein product is a salted and smoked meat product.
 18. The method of claim 1, wherein said cured protein product is a fish.
 19. A method of freezing a cured protein product to reduce purge produced from cured protein product comprising the steps of: (a) preparing a brine comprising at least 0.1% by weight of cruciferous oil, between about 30 and 50% by weight of glycol and between about 5 and 15% by weight of an inorganic salt, the balance being water; (b) cooling the brine to a temperature between about −22 and −43.6° F.; (c) vacuum packaging said cured protein product; (d) placing said cured protein product on a perforated board such that the entire surface of said cured protein product is exposed to the cooled brine; and (e) immersing said cured protein product in the brine until said cured protein product is completely frozen.
 20. The method of claim 19, wherein the brine includes between about 0.1 and 1% by weight of a cruciferous oil.
 21. The method of claim 19, wherein the oil is rapeseed oil.
 22. The method of claim 19, wherein the brine includes between about 0.1 and 0.5% by weight of a cruciferous oil, between about 35 and 45% by weight of a glycol, between 7 and 13% by weight of an inorganic salt and a balance of water.
 23. The method of claim 19, wherein said cured protein product is vacuum packaged in a plastic bag.
 24. The method of claim 19, wherein said perforated board is a plastic mesh.
 25. The method of claim 19, wherein said cured protein product is a salted meat product.
 26. The method of claim 19, wherein said cured protein product is a salted and smoked meat product.
 27. The method of claim 19, wherein said cured protein product is a fish. 